JPH1077967A - Rapid regenerative cryopump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To considerably shorten time required for temperature rise of a gas suction face and for cooling at the time of regenerating work by providing a diaphragm driving means for attaching/detaching a diaphragm provided at the upper face of a cryopanel. SOLUTION: In case of exhaust performance being lowered due to the progress of agglutination of gas to the upper face of a diaphragm 2, a rapid regenerative cryopump 1 is regenerated. When a current is carried from a conductor 3e to raise the temperature of a coil 3d, the coil 3d is elongated by the action of a shape memory alloy so as to lift the diaphragm 2 through a connecting rod 3b and a ring body 2a. With the lapse of time, heat of the coil 3d reaches the ring body 2a via a heat buffer 3c so as to raise the temperature of the diaphragm 2, but since the diaphragm 2 is separated from a cryopanel 1b at this time, there is no generation of such defectiveness that the cryopanel 1b cooled to extremely low temperature is heated by heat transfer or radiation from the diaphragm 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cryopump used for evacuation for generating an ultra-high vacuum or an ultra-high vacuum in a nuclear fusion apparatus, a thin film industry, or the like.

[0002]

2. Description of the Related Art A cryopump is an ultrahigh vacuum pump of a type in which a very low temperature panel surface called a cryopanel is placed in a pump, and gas is condensed on the surface to exhaust gas.

[0003] Cryopumps have excellent pumping speed and ultimate pressure, but because they are pool-type pumps,
When a certain amount of gas adheres to the surface of the cryopanel, the exhaust performance deteriorates rapidly. In order to recover the reduced exhaust performance, a regeneration treatment by heating with a heater is performed, which raises the temperature of the cryopanel surface to vaporize the condensed gas on the cryopanel surface and separates the condensed gas on the cryopanel surface for another regeneration. It is evacuated by a vacuum pump, and the regeneration work must be performed periodically.

[0004]

When a conventional cryopump is regenerated, a refrigerator for cooling the cryopanel is stopped, and the cryopanel is heated by a heater or the like.

However, at the time of this heating, the temperature of the pipes of the refrigerant flow path connected to the cryopanel, the supporting members of the cryopanel, and the like are also raised at the same time. There is a problem that it takes a long time to raise the temperature because the heating temperature is limited due to the component material.

Also, when the cryopump is restarted after the regenerating operation, there is a problem that it takes a long time to cool the cryopanel surface due to the same heat capacity.

[0007] Further, when the time required for raising and cooling the temperature of the cryopanel is shortened by making these heaters and refrigerators powerful, the cryopanel and the refrigerant flow path receive a large thermal shock. And there is a danger that cracks and destruction will occur and the material of the components will deteriorate.

An object of the present invention is to provide a rapid regeneration cryopump capable of solving these problems and performing a regeneration operation in a short time.

[0009]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a diaphragm made of a thin metal plate having an airtight periphery formed on a top surface of a cryopanel so as to be detachable and detachable. And a heating means for heating the diaphragm.

[0010]

FIG. 1 shows a first embodiment of the present invention.
And FIG.

FIG. 1 shows a rapid regeneration cryopump 1 according to the present invention.
FIG. 2 shows a cross-sectional view at the time of exhaust operation, and FIG. 2 shows a cross-sectional view at the time of regeneration of the rapid regeneration cryopump 1.

The diaphragm 2 is made of a thin metal plate, the periphery of which is hermetically bonded to the cryopump housing 1a via an annular insulator 3f, and the lower surface of which is made of a metal ring having good thermal conductivity. It is connected to the diaphragm driving means 3 via the body 2a.

The diaphragm driving means 3 includes a connecting rod 3b,
It comprises a heat buffer 3c and a coil 3d made of a shape memory alloy.

The coil 3d made of a shape memory alloy is formed so as to expand at high temperature and to contract at low temperature.
The coil 3d is provided with a heater, and the temperature of the coil 3d can be increased by energization.

Reference numeral 1b denotes a cryopanel, on the back side of which a refrigerant flow path 1c is arranged so that the cryopanel 1b can be cooled down to an extremely low temperature. In addition, 1d and 1e respectively indicate a supply port and a discharge port of the refrigerant.

Reference numeral 1f denotes an inner cylinder having a vent, which is connected to the cryopanel 1b via a cylindrical heat insulator 3g and fixed to the bottom of the cryopump housing 1a.

Reference numeral 4 denotes a turbo-molecular pump, which functions to maintain the lower part B of the diaphragm 2 in an ultra-high vacuum.

Reference numeral 5 denotes an auxiliary pump for the turbo molecular pump 4.

Next, the operation of the first embodiment will be described.

During the evacuation operation of the rapid regeneration cryopump 1, the diaphragm 2 is in close contact with the upper surface of the cryopanel 1 b, and the very low temperature refrigerant flows through the refrigerant flow path 1 c, thereby making the diaphragm 2 equivalent to the cryopanel 1 b. Is kept at a low temperature. Therefore, gas molecules in the upper part A of the diaphragm 2 are condensed on the upper surface of the diaphragm 2 and exhausted.

When the gas deposition on the upper surface of the diaphragm 2 progresses and the exhaust performance deteriorates, the quick regeneration cryopump 1 is regenerated.

In this case, first, the diaphragm driving means 3
Is operated to separate the diaphragm 2 from the upper surface of the cryopanel 1b.

That is, power is supplied from the conductor 3e to the coil 3d.
When the temperature is raised, the coil 3d is extended by the action of the shape memory alloy, and operates to lift the diaphragm 2 via the connecting rod 3b and the annular body 2a.

The heat buffer 3c is for preventing the heat of the coil 3d from being rapidly transmitted to the annular body 2a and the diaphragm 2. That is, while the diaphragm 2 has not yet separated from the upper surface of the cryopanel 1b, the coil 3
This is because, when the heat of d arrives at the diaphragm 2, a problem occurs in that the heat is transmitted to the cryopanel 1b cooled to an extremely low temperature.

With the passage of time, the heat of the coil 3d reaches the annular body 2a via the heat buffer 3c and raises the temperature of the diaphragm 2. At this time, since the diaphragm 2 is already separated from the cryopanel 1b, the cryopanel 1b Is not heated by heat transfer or by radiation from the diaphragm 2.

That is, the diaphragm 2 and the cryopanel 1
Each of the separation surfaces b is mirror-plated with gold, silver or copper, which has good heat conductivity and low emissivity.

Now, the diaphragm 2 and the cryopanel 1b
S (m ² ) is the area of the surface facing the separation surface of the cryopanel 1
Assuming that the temperature of b is Tp (K), the temperature of the diaphragm 2 at the time of reproduction is Td (K), the emissivity of the release surface is ε, and the Stenfan-Boltzmann constant is σ (W / m ² K ⁴ ), Of heat transfer by radiation to cryopanel 1b
(W) is obtained by equation (1).

[0028]

(Equation 1) … (1)

Therefore, the diameter of the separation surface is 200 mm, the emissivity ε of the separation surface is 0.02, the temperature Tp of the cryopanel 1b is 0K, the temperature Td of the diaphragm 2 is 293K, and the Stefan-Boltzmann constant σ is 5.67 × Assuming 10 ⁻⁸ W / m ² K ⁴ , the heat transfer amount Q due to radiation from the diaphragm 2 to the cryopanel 1 b is 0.26 W, which is a small value that does not pose any problem from the heat removal capacity of a normal cryopump. is there.

As described above, the amount of heat transferred from the diaphragm 2 to the cryopanel 1b during reproduction by radiant heat transfer is very small, and no problem occurs.

Further, since the diaphragm 2 is made of a thin metal plate, it has a small heat capacity.
Heats up rapidly and begins to emit condensed gas. The released gas is discharged by another regeneration vacuum pump (not shown).

Since the lower part B of the diaphragm 2 is also kept in an ultra-high vacuum by the molecular pump 4, no gas is condensed on the surface of the cryopanel 1b. Good heat transfer is maintained.

Also, the diaphragm 2 and the cryopanel 1b
Also, when the release surface is separated, it is easily performed without resistance.

On the other hand, during the regeneration, the refrigerant is kept flowing in the refrigerant flow path 1c disposed in the cryopanel 1b. Therefore, when the regeneration is completed, the power supply to the heater is stopped, the length of the coil 3d is shortened, and the diaphragm 2 Is brought into close contact with the cryopump 1b, whereby the diaphragm 2 can be rapidly cooled and return to the exhaust operation.

As described above, the rapid regeneration cryopump 1 of the present invention reduces the heat capacity of the diaphragm 2 serving as the gas adsorption surface by
Since the heat capacity of the conventional cryopanel can be reduced to 1/100 or less, the time required for raising and cooling the temperature of the gas adsorption surface during the regeneration operation is greatly reduced.

Further, since the cryopanel 1 is always kept at an extremely low temperature, there is no thermal shock to the cryopanel 1b during the regenerating operation.

Further, the rapid regeneration cryopump 1 of the present invention
Can be continuously exhausted by combining a plurality of.

Note that, instead of providing a heater with the coil 3d made of a shape memory alloy, the coil 3d itself may be used as a heating element.

FIGS. 3 and 4 show a second embodiment of the present invention.
This will be described below.

FIG. 3 shows the second structure of the rapid regeneration cryo pump 1.
1 shows a cross-sectional view of the embodiment at the time of reproduction.

The diaphragm driving means 6 comprises a connecting rod 6b having a heat insulator 6a at the tip and a telescopic driving part 6c.
Reference numeral 7 denotes an annular heater plate fixed to the cryopump housing 1a. Note that a solenoid, a linear motor, an air-operated cylinder sealed with bellows, or the like is used for the expansion / contraction drive unit 6c. FIG. 4 shows the bellows 6
d, an air operated type using an air cylinder 6e and a piston 6f.

The second embodiment differs from the first embodiment in that a diaphragm driving means 6 is provided in place of the diaphragm driving means 3 in the first embodiment, and a heater plate 7 is provided. It is different from the form.

The operation of the second embodiment will be described.

While the diaphragm 2 is in close contact with the cryopanel 1b during the evacuation operation, the diaphragm 2 is lifted by the diaphragm driving means 6 and the upper surface of the diaphragm 2 is pressed against the heater plate 7 during reproduction. Then, electricity is supplied from the conductor 3e to the heater plate 7
As a result, the temperature of the diaphragm 2 is raised to release the condensed gas.

At the time of reproduction in the second embodiment, since the diaphragm 2 is heated after being separated from the cryopanel 1b and the temperature rises, there is no problem that the cryopanel 1b is heated together.

FIG. 5 shows a rapid regeneration cryopump 1 according to the present invention.
FIG. 11 is a cross-sectional view of the third embodiment during reproduction.

In FIG. 5, the diaphragm driving means 6
Is the same as that of the second embodiment, except that a heater 8 composed of a spiral heating wire is installed on the diaphragm 2 instead of the heater plate 7, and the heater 8 is supplied with electricity from the conductor 3e during reproduction. Thus, the diaphragm 2 is directly heated by the heater 8.

That is, in the second and third embodiments, the temperature of the diaphragm 2 can be controlled by adjusting the amount of heat generated by the heater plate 7 or the heater 8 in addition to the advantage that the diaphragm 2 can be heated after being separated from the cryopanel 1b. The feature is that it can be controlled directly.

Although the method of cooling the cryopanel 1b of the present invention with a refrigerant has been described, a cold head of a cryopump using helium gas which is commercially available may be used.

[0050]

As described above, according to the present invention, the time required for raising and cooling the temperature of the gas adsorbing surface during the regenerating operation is greatly reduced, and the cryopanel and the coolant flow path are always kept in a cooled state. Therefore, it is possible to provide a quick-regeneration cryopump having a safe structure in which the cryopump does not receive a thermal shock.

[Brief description of the drawings]

FIG. 1 is a sectional view of an evacuation operation of a rapid regeneration cryopump according to a first embodiment of the present invention.

FIG. 2 is a sectional view at the time of reproduction of the above.

FIG. 3 is a sectional view at the time of regeneration of a rapid regeneration cryopump according to a second embodiment of the present invention.

FIG. 4 is a sectional view when an air-operated cylinder is used in the second embodiment.

FIG. 5 is a sectional view at the time of regeneration of a rapid regeneration cryopump according to a third embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Rapid regeneration cryopump 1b Cryopanel 2 Diaphragm 3, 6 Diaphragm drive means 3c Heat buffer 7, 8 Heating means

Claims (10)

[Claims] 1. A diaphragm made of a thin metal plate whose periphery is formed airtight is provided on a top surface of a cryopanel so as to be detachable and detachable, and a diaphragm driving means for detaching and attaching the diaphragm and heating for heating the diaphragm are provided. A rapid regeneration cryopump characterized by comprising means. 2. The rapid regeneration cryopump according to claim 1, wherein said diaphragm driving means uses a shape memory alloy which expands and contracts with a change in temperature. 3. The rapid regeneration cryopump according to claim 1, wherein said heating means comprises a heater attached to said shape memory alloy. 4. The rapid regeneration cryopump according to claim 1, wherein a heat buffer is interposed between the shape memory alloy and the diaphragm. 5. The rapid regeneration cryopump according to claim 1, wherein the lower side of the diaphragm is made to have an ultra-high vacuum. 6. A molecular pump for evacuating the lower side of the diaphragm to a vacuum.
The rapid regeneration cryopump according to the above. 7. The rapid regeneration cryopump according to claim 1, wherein said heating means comprises a heater plate which comes into contact when said diaphragm separates from said cryopanel. 8. The apparatus according to claim 1, wherein said heating means comprises a heating wire adhered to a peripheral portion of said diaphragm.
The rapid regeneration cryopump according to the above. 9. The rapid regeneration cryopump according to claim 1, wherein the diaphragm driving means is a solenoid, a linear motor, or an air-operated cylinder sealed with a bellows. 10. The rapid regeneration according to claim 1, wherein gold, silver, copper, or the like is plated on both of the separation surfaces of the diaphragm and the cryopanel to be separated from each other to form a mirror surface. Cryopump.